Process of making primary ammonium phosphate.



'S. PEAOOGK. PROCESS OF MAKING PRIMARY AMMONIUM PHOSPHATE.

APPLICATION FILED SEPT. 2, 1909 988,734.

Patented Apr. 4, 1911 phosphate rock is ordinarily treated with To all whom it may concern:

Crude calcium phosphate aO),,,P. .O, as

SAMUEL PEACOCK, 0F CHIC-AGD, ILLINOIS,

COMPANY, OF NEW YORK, II.

ASSIGNOR T0 AMERICAN" GYANAMID A CORPORATION OF MAINE.

Pnoonss cs MAKING PRIMARY Ammonium PHOSPHATE.

Specification of Letters 'Patent.

Patented Apr, 4, 1911.

Application filed September 2, 1909. Serial No. 515,807.

Be it known that l, Sin tour, Pmcocit, a citizen of the llnitcd tltates, residing at Chicago, in the county cl Cool: and State of Illinois, have invented certain new and useful Improvcrnents in Processes of Making Phosphate Ammonia; undl dohereby declone the following to, be a full, clear, and exact description of the invention, such as will enable others skilled in thc art to which it appertains to make and use the same.

This invention relates to a process for making phosphate of ammonia, from comlllQl'ClZll acid phosphate and sulfate 01 ammonia, in a sin'iple and comparatively inexpensive manner, and to t is end, the invention consists in the novel steps and combinations of stepsconstituting my process, more fully v hereinafter disclosed and particularly pointed out in the cl'ainiis.

mined contains lime ,(CaOlnnd phosphoric anhydrid orphospliorous, pentoxid (P 0 combined in the proportions of three (3) chemical. equivalents of the former to one (1) chemical equivalent of the latter. In this state of combination, the phosphoric anhydi'id is neither soluble in water, nor in the Weak acids of the soil. Hence, in order to render the phosphoric anhydrid available to the assin'iilating powers of growing plants,

sulfuric acid, which combines with somewhat less than two thirds the lime already combined with the phosphates, which forms hold the phosphoric anhydi'id so loosely that growing plants are enabled to assimilate the phosphoric ei'ihydrid combined there with.

Thetwo terms of lime phosphates known respectively as mono-calcium phosphate and di-calciuno phosphate, may be obtained by the following reactions:

The monoand (ii-calcium phosphates are of practically equal agricultural value, and are termed available forms of phosphorus by the various State fertilizer control laws,

:icid spin-alto, it would be a saving of sulfuric acid to convert the triculciuul phospate into di-calcium phosphate only, but there are practical ditliculties in securing such exact work in routine factory operations, Consequently, as a practical tact. (501111]:610131 and phosphate contains aluzut oue-iourll of its total amilable phosphoric anhydrid in the form of di-calcium peosphate, and three-fourths in the term of mono-calcium phosphate. The sulluric acid used in producing available phosphor': acid (anhydl'id) remains in the acid phosphate, in the form olsullale of lime: which on some soils is of no utility as u lcrlilizcl'. l

The object of my process more specifically stated is to avoid these objections, and to convert the phosphoric acid contained in the acid phosphllte, into phosphate of ammonia, by leaching the same, for example, from the insoluble sulfates otlhnes'and producing thereby a Water soluble, (and highly available form ofphosphoric acid, all as will now appear.

Referring to the accompanying drawings forming a part of this specification in which the figure is a diagrammatic View of an apparatus involving the process z-l represents any suitable container, 2. any suitable heating means, and 3 any suitable mixing or stirring means.

Steam is preferably led in at 4, through the coil 2, and exits at weighed quantity of commercial acid phosphate to which has been added a sufficient uantity of commercial ammonium sulfate to chemically combine with the said ph0sy'ahute and both in a state of fine subdivision is nextplaced in the vessel 1. The said phosphate and sulfate are so iproportioned as to form the monoand di-calciuni phosphates in accordance with the follow ing cquationszpasses Suflicient water to dissolve the ammonium sulfate having been added. to the digestion vessel, heat is turned on, and the telnpertv lure maintained at any suitable point below 80 (1., preferably about 10 or 15 degrees below 80 C. while the whole c ,u-ge is conprinciples of my ary ammonium phosphate Will be driven stantly agitated by the mechanical stirrer 3 or by other means. After the decomposition of the phosphates, Which may be deter.-

mined by a chemical examination,'the con-' tents olthe digester is discharged into anysuitable filter, through the manhole 6; then thoroughly Washed with hot Water, and the solution thus obtained is evaporated to crystallization in any suitable apparatus pref erably a vacuum pan.

oil as gaseous ammonia; and if desirable this latter may he condensed-and recovered in ordinary cooling poils, not shown.

The advantages of my process depend largely upon the conuiarath cly inexpensive production of a phosphate containing; all its phosphoric acid available as plant food, and at the same time in a form free of sulfate of lime, or other more or less harmful substances, such as sulfate of iron or alum cake, of which commercial acid phosphates always contain a considerable quantity. The conversion of the secondary ammonium phosphate into primary ammonium phosphate may for example, take place at a temammonia from acid calcium phosphate which consists in mixing in a Water solution finely divided crudev acid calcium phossphate' and ammonium sulfate; in maintaining 'the.,'temperature of said solution below 80 C.; filtering out the mixed phosphates 'of ammonia; in concentrating the filtrate to the point where substantially all the secondformed is converted into prima-r nium phosphate, thereby driving-on gaseous ammonia; and in suitably recovering the latter; substantially as described. v In testimony whereof, I ,aflix my signature, in presence of two Witnesses.

SAMUEL PEAGOCK. Witnesses p T. .A. lVrrnnnsroon,

'Gno. B. Prr'rs.

2. The process of making phosphate of ary ammonium phosphate that has been ammo-- 

